Continuous pressure molten metal supply system and method

A method of operating a molten metal supply system to supply molten metal to a downstream process at substantially constant molten metal flow rates and pressures, with the system comprising:

• a molten metal supply source;
• a plurality of injectors, each comprising a housing configured to contain molten metal and in fluid communication with the molten metal supply source;
• and a piston reciprocally operable within the housing, with the piston movable through a return stroke and a displacement stroke, and with the piston having a pistonhead for displacing the molten metal from the housing;
• and
• a liquid chamber located above and in fluid communication with the housing of each of the injectors, and containing a liquid chemically resistive to the molten metal contained in the molten metal supply source,
• the method comprising the steps of:
• serially actuating the injectors to move the pistons through their return and displacement strokes at different times thereby providing substantially constant molten metal flow rate and pressure to the downstream process;
• and
• supplying liquid from the liquid around the piston head and between the molten metal received into the housing and the liquid chamber of each of the injectors during the return and displacement strokes of the pistons,
• wherein at least one of the pistons moves through its displacement stroke while the remaining pistons move through their return strokes to provide the substantially constant molten metal flow rate and pressure to the downstream process.